This invention relates to a method for rollback from a snapshot to a volume with log in a storage system.
In the storage system in recent years, application of recovery from disaster (disaster recovery) using remote copy has been increased. Disaster recovery is aimed at continuation of business when a failure occurs due to disaster by copying data from an operating site (primary site) to a remote site (secondary site).
In the conventional computer systems, only the database process of the businesses having critical mission among those which give the largest influence on continuation of business has been considered as an object of copy to the remote site (remote copy). However, in recent years, non-database process of the peripheral businesses is also gradually considered as an object of remote copy in view of further reducing non-service period when a failure occurs. For the remote copy of the businesses having critical mission, synchronous copy for immediately transferring updated data using an expensive leased line has been conducted in general in order to prevent missing of data due to delay of copy. On the other hand, for the businesses having no critical mission, asynchronous copy for transferring intermittently the updated data at a time is generally conducted in order to save communication cost because missing of the latest data can be permitted to a larger extent than the database process (e.g., U.S. Pat. No. 6,668,264).
Service stoppage in disaster recovery occurs in the timing of fail-over in which the secondary site takes over businesses of the primary site when a failure occurs and the timing of fail-back in which the primary site immediately takes over businesses of the secondary site when the primary site recovers from the failure. In the fail-back mode, after the data of the primary site is synchronized with the data of the secondary site, the remote copy operation from the primary site to the secondary site is restarted. A series of disaster recovery beginning from the fail-over mode to the fail-back mode can be completed by returning the business which has been taken over by the secondary site to the primary site.